WO2011018841A1

WO2011018841A1 - Inkjet recording device and printing head

Info

Publication number: WO2011018841A1
Application number: PCT/JP2009/064170
Authority: WO
Inventors: 原田　信浩; 宮尾　明; 堀川　康治; 久梅津; 拓也盛合
Original assignee: 株式会社日立産機システム
Priority date: 2009-08-11
Filing date: 2009-08-11
Publication date: 2011-02-17
Also published as: US20120194586A1; CN102470669B; US8764169B2; IN2012DN00864A; EP2465681A4; JPWO2011018841A1; EP2465681B1; EP2465681A1; CN102470669A; JP5190146B2

Abstract

Provided is an inkjet printing technology which prevents the character widths of printing results from increasing, even when the transfer speed of a subject to which printing is to be performed is high. In an inkjet recording device, a plurality of nozzles are arranged such that the nozzles are orthogonally intersecting with the deflecting direction determined by deflection electrodes, an ink jetted from the nozzles is electrostatically charged by means of charging electrodes of the same number as the number of the nozzles, and each electrostatically charged particle is deflected within one deflection field wherein the deflection electrodes are composed of a pair of positive and negative deflection electrodes. Furthermore, the inkjet recording device is provided with a function of independently adjusting the value of a charging voltage to be applied to each of the charging electrodes and application timing of the charging voltage.

Description

Ink jet recording apparatus and print head

The present invention relates to an ink jet recording apparatus (ink jet printer) and a print head used therefor, for example, an industrial ink jet recording apparatus used for product marking and a print head used therefor.

First, the control technique when the conveyance speed of the substrate to be printed of the conventional ink jet recording apparatus is changed will be described with reference to FIG. In an ink jet recording apparatus, ink particles ejected from one nozzle are used when printing on a printing object (also referred to as “work”). When the conveyance speed of the printed material is relatively low, the charging voltage is applied by regarding the ink particles ejected from one nozzle as a charging target at a ratio of one to a plurality of ink particles. The upper part of FIG. 1 shows an example in which one of the two created ink particles is to be charged, and this is defined as a particle usage rate of 1/2. In order to reduce the character width of the printed result at the same conveyance speed, it is possible to increase the particle usage rate as shown in the middle of FIG. In this example, the particle usage rate is changed to 1/1.

Also, as shown in the lower part of FIG. 1, the print character width can be controlled by leaving each scan interval. In this case, the creation cycle of the ink particles ejected from the nozzles is set constant so as to obtain an optimal ink particle shape based on the ink pressure and ink viscosity, etc., and the ink particles are charged and deflected to a predetermined position. It is supposed to be. When the charging voltage is fixed, the character width of the printing result tends to increase as the conveyance speed of the printing object increases.

FIG. 1 shows an example of performing one-step printing. On the other hand, for example, as shown in Patent Document 1, in the case where two or more stages of printing are performed, two or more nozzles are arranged in a print head, and an ink jet recording apparatus that performs printing corresponding to each nozzle and stage Has been devised. According to this method, the system has a system of charging voltage and deflection voltage according to the number of each nozzle, and in order to reduce the character width of the printing result in high-speed printing when performing multi-stage printing. It is an effective method.

US Pat. No. 5,457,484

However, when one-step printing is performed using the technique disclosed in Patent Document 1, the character width of the printing result in high-speed printing cannot be reduced. If the character width of the printing result is widened, it is considered that the printed matter protrudes from the printing area of the printing object, resulting in defective printing. Therefore, it is necessary to realize printing control so that the character width does not increase even when the conveyance speed of the substrate to be printed becomes high.

By the way, as a technique for preventing the character width of the printing result from being widened even when the conveyance speed of the substrate to be printed becomes high, the particle usage rate used for printing the ink ejected from the nozzle described in the previous stage It is effective to increase the value or to shorten the production cycle of the ink ejected from the nozzles.

However, in the former, the particle usage rate 1/1 is the limit, and the range that can cope with high speed is limited. The latter is a specification that is set in advance so as to obtain an optimal ink particle shape based on ink pressure, ink viscosity, etc., and if only the ink creation cycle is changed, printing defects will occur due to defective ink particle formation. Have a factor that occurs.

Therefore, in order to realize speeding up of a particle usage rate of 1/1 or more, it is possible to perform printing using a plurality of nozzles. However, the technique shown in Patent Document 1 realizes printing of two or more stages at a printing speed of one stage. As described above, when the conveyance speed of the substrate is increased, the printing result is The character width cannot be prevented from widening.

In addition, a plurality of nozzles are housed in the print head, and the charging voltage is binarized to charge the ink particles, thereby separating the presence and absence of deflection in the deflection electrode, and the ink particles collected by the gutter There is a method of separating particles used for printing. However, this method has a problem that the number of nozzles increases, reliability is deteriorated, and cost is increased.

The present invention has been made in view of such a situation, and in an ink jet recording apparatus, even when the conveyance speed of an object to be printed is increased, the character width of the printing result is not increased, and the printing quality is improved. The technology for improving is provided.

In order to solve the above-described problems, the present invention is configured so that the arrangement direction of a plurality of nozzles is orthogonal to the deflection direction of ink particles in an ink jet recording apparatus. The ink ejected from a plurality of nozzles is charged by the same number of charging electrodes as the nozzles, and each charged particle is deflected in one deflection electric field formed by a pair of positive and negative deflection electrodes, and applied to each charging electrode. The voltage value of the charging voltage to be applied and the application timing of the charging voltage are configured to have a function that can be adjusted independently.

That is, an ink jet recording apparatus according to the present invention is an ink jet recording apparatus that prints on a substrate to be conveyed, and includes a plurality of nozzles, a plurality of charging electrodes, a deflection electrode, an input unit, and a control unit. It is equipped with. The plurality of charging electrodes are arranged corresponding to the plurality of nozzles, and charge the ink particles ejected from each of the plurality of nozzles. The deflection electrode is a means for deflecting charged ink particles. The arrangement direction of the plurality of nozzles is orthogonal to the deflection direction of the charged ink particles. The control unit expands the print characters input from the input unit into a dot matrix, assigns each dot data to a plurality of nozzles, ejects ink from the plurality of nozzles, and the value of the charging voltage applied to the plurality of charging electrodes. And the application timing are controlled. With such a configuration, it is possible to print a character string of one stage on a printing object using a plurality of nozzles. The deflection electrode is composed of a pair of flat plate electrodes regardless of the number of nozzles and charging electrodes. In addition, the control unit prints one row of character strings on the printing object by sequentially printing dot rows from a plurality of nozzles.

Also, the input unit has a printing condition setting unit that can set printing conditions independently for each of the plurality of nozzles. In this case, the control unit controls the ink ejection operation, the charging voltage value, and the application timing in accordance with the printing conditions set by the printing condition input unit.

More specifically, when adjustment of the print character height is instructed by the print condition setting unit, the control unit adjusts the value of the charging voltage applied to the charging electrode corresponding to the nozzle whose print character height should be adjusted. To do. When the print condition setting unit instructs the adjustment of the print start timing, the control unit adjusts the application timing of the charging voltage applied to the charging electrode corresponding to the nozzle whose print start timing is to be adjusted. In addition, when the print condition setting unit is instructed to adjust the print row interval, the control unit creates ink particles that do not print in the print row interval according to the adjustment value of the print row interval for each nozzle. By applying a charging voltage that is inserted in units of dots to the charging electrode, the print row interval is adjusted. In addition, when the printing condition setting unit is set so that the particle usage rate of the ink particles ejected from each nozzle is different, the control unit controls the inclination of the dot row generated by each nozzle based on the usage rate. By doing so, a special print pattern is realized.

Further features of the present invention will become apparent from the best mode for carrying out the present invention and the accompanying drawings.

According to the present invention, it is possible to improve the printing quality by preventing the character width of the printing result from being widened even when the conveyance speed of the substrate is increased.

It is a figure which shows the example of printing (medium-speed printing) in the conventional 1 nozzle, and the charging voltage waveform example (1). It is a figure which shows the example of printing (medium speed printing) in the conventional 1 nozzle, and the example (2) of a charging voltage waveform. It is a figure which shows the example of a printing in the conventional 1 nozzle, and the example of a charging voltage waveform when a workpiece | work speed is increased. 1 is a block diagram showing an overall circuit configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of a print head. It is a figure which shows the example of printing (high-speed printing) in the 2 nozzle print head structure of this embodiment, and the example of a charging voltage waveform (1). It is a figure which shows the example of printing (high-speed printing) in the 2 nozzle print head structure of this embodiment, and the example of a charging voltage waveform (2). It is a figure which shows the example of defective printing in the 2 nozzle print head structure of this embodiment, the example of improvement printing (high-speed printing), and the example of a charging voltage waveform. It is a figure which shows the example of application printing (special pattern) which becomes possible when the 2 nozzle print head structure of this embodiment is implemented. The upper part of FIG. 9 shows the case where the print start timing is controlled for each nozzle, and the lower part of FIG. 9 shows the case where the particle usage rate is controlled for each nozzle. It is a figure which shows the example of a setting on the setting screen (GUI) by this embodiment. It is a print control example using the setting screen (GUI) by this embodiment, Comprising: It is a figure which shows a print start timing chart. It is a print control example using the setting screen (GUI) by this embodiment, Comprising: It is a figure which shows a print result and the example of a charging voltage. It is a figure which shows the example of distribution control of the printing dot data by this embodiment.

In the present invention, by executing one-step printing using a plurality of nozzles, the character width of the printed result is not increased even when the conveyance speed of the substrate is increased.

However, in order to realize this technology, there are two main issues. That is, the first problem is that the vertical dot pitch printed from each of the plurality of nozzles is not uniform, that is, the print character height is different due to the difference in the print character height of the ink ejected from each nozzle. It is. The print character height is determined by the speed of the ink particles ejected from the nozzle, the amount of charge charged by the charging electrode, the strength of the deflection electric field formed in the deflection electrode, etc. fluctuate. Therefore, for this problem, it is necessary to have a mechanism for adjusting the print character height for each nozzle. In the present invention, it is considered that the means for adjusting the charging voltage value independently for each nozzle is most effective.

Also, the second problem can be considered that the print quality is deteriorated due to the fact that the horizontal dot pitches printed from a plurality of nozzles are not uniform. For this problem, it is most effective to use a configuration in which the nozzles are arranged in the horizontal direction (perpendicular to the deflection direction) and to independently control the timing for starting printing from each nozzle. It is done.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be noted that this embodiment is merely an example for realizing the present invention, and does not limit the technical scope of the present invention. In each drawing, the same reference numerals are assigned to common components.

<Circuit configuration of inkjet recording apparatus>
FIG. 4 is a block diagram showing an overall circuit configuration of the ink jet recording apparatus according to the embodiment of the present invention. FIG. 4 shows a circuit configuration of an ink jet recording apparatus having two nozzles, but the number of nozzles may be three or more.

As shown in FIG. 4, the ink jet recording apparatus includes an MPU (microprocessing unit) 1 that controls the entire ink jet recording apparatus, a ROM (read only memory) 2 that stores programs and the like, and a temporary storage in the ink jet recording apparatus. Random access memory (RAM) 3 for storing data, an input panel 4 for inputting contents to be printed, which also has a display device, a pump for pressurizing ink, a pressure reducing valve and a solenoid valve for adjusting pressure, etc. A circulation control circuit 5 for controlling the circulation system component 6, a deflection D / A converter 20 for digital-analog conversion of data instructed by the MPU 1, an AMP 21 for amplifying a signal after D / A conversion, and a charging system circuit A_51 The charging system circuit B_52, the print head 47, and the object to be printed (work) 49 are detected. A work sensor 48 is provided with a printing object detecting circuit 34 to determine the print start timing based on the detection result of the work sensor 48 is a desired timing, the. Each block other than the print head 47 and the work sensor 48 is connected to the MPU 1 via the bus line 7 and controlled by the MPU 1.

The charging system circuit A_51 includes a print start signal command circuit A_8 that outputs a print start signal in accordance with a command from the MPU 1, a charge voltage generation circuit A_9 that generates a charge voltage in response to the timing of the print start signal, and a digital charge voltage value. Charging D / A converter A_14 for analog conversion, AMP 15 for amplifying the D / A converted charging voltage value, particle usage rate switch A_10 for setting the particle usage rate, and setting the ink particle creation cycle Excitation setting switch A_11, oscillator A_12, phase detection circuit A_13 for detecting the phase of the ink particles emitted from the nozzle, and frequency division for dividing the oscillation clock based on information on the usage rate and the ink particle creation cycle A counter A_16; an excitation voltage generating circuit 17 for generating an excitation voltage; and an AMP 18 for amplifying the excitation voltage value. There. Since the charging system circuit B_52 has the same configuration as that of the charging system circuit A_51, the description thereof is omitted.

The print head 47 has two print head components. The print head constituting unit A operates a nozzle A_35 that discharges ink, an electrostrictive element A_36 that operates according to an excitation voltage to atomize ink, a charging electrode A_37 that charges ink particles, and a timing for creating ink particles. A phase search sensor A_38 for searching,

deflection electrodes

45 and 46 for deflecting ink particles, and a gutter A_39 for collecting ink particles that have not been used for printing are provided. The other print head component B has the same configuration as the print head component A.

Subsequently, an outline of a control operation for performing printing with ink ejected from the nozzle A_35 will be described. First, the charging signal generation circuit A_9 creates and stores various data such as voltage data and timing data for charging the ink particles based on the printing content data input from the input panel 4, and the printing start signal command circuit A_8. The data is transferred to the charging D / A converter A_14 in accordance with the print start timing in accordance with the instruction from. The voltage value converted into analog by the charging D / A converter A_14 is amplified by the AMP 15 and applied to the charging electrode A_37 in accordance with the print start timing.

The operator uses the particle usage rate switch A_10 to set the usage rate of the charged particles used for printing. The higher the usage rate, the higher the printing speed becomes possible, but the printing quality deteriorates due to the influence of printing distortion, and vice versa when the usage rate is low. In addition, the operator uses the excitation setting switch A_11 to determine the creation cycle of the ink particles ejected from the nozzles.

The oscillation clock output from the oscillator A_12 is divided by the frequency division counter A_16 based on the information of the particle usage rate switch A10 and the excitation setting switch A11, a timing signal is generated, and the charging signal generation circuit A_9 and the excitation voltage generation are generated. It is input to the circuit A_17. The signal output from the excitation voltage generation circuit A_17 is amplified by the AMP 18 and applied to the electrostrictive element A_41. The electrostrictive element A_36 converts the electric signal from the AMP 18 into vibration, pressurizes the ink, and ejects ink particles.

The phase search sensor A_38 searches the creation timing of the ejected ink particles. In order to perform optimal printing, it is necessary to apply a charging voltage in synchronization with the ink particle creation timing. Therefore, the detected timing is fed back to cause a phase shift (the timing of ink particle ejection and charging voltage application timing). Shift) is adjusted. More specifically, the signal detected by the phase search sensor A_38 is amplified by the AMP 19 and digitally converted by the phase detection circuit A_13, and then the ink particle creation timing is determined by the MPU1. Then, the charging timing (phase) information at which the MPU 1 is optimal is output to the charging signal generation circuit A_9.

Ink particles charged by the charging electrode A_37 are deflected by flying through an electric field formed by applying a DC voltage to the plus deflection electrode 46 and grounding the minus deflection electrode 45, and are used for printing. Jumps over the gutter A44 and is ejected from the print head 47, adheres to the work 49, which is the object to be printed, and is used for printing. At this time, deflection is performed according to the charge amount of the ink particles, the deflection amount of the ink particles having a large charge amount is large, and the deflection amount of the particles having a small charge amount is small. Further, the magnitude of the DC voltage applied to the plus deflection electrode 46 is obtained by converting the data instructed from the MPU 1 into digital / analog by the deflection D / A converter 20 according to the character height information set from the input panel 4, and by the AMP 21. The configuration is variable depending on the configuration to be amplified.

Ink that was not used for printing, that is, ink particles that were not charged and ink particles that were charged for phase search, are collected from the gutter A44 and supplied again to the nozzle A_35 by the circulation system component 6 such as a pump.

The printed material 49 is conveyed on the conveyor 50, and is printed in a direction substantially perpendicular to the ink ejection direction and the ink deflection direction (when the print head 47 is inclined (see FIG. 5)). (Only the ink outflow direction is orthogonal to the transport direction). The print start timing is controlled by the MPU 1 through the workpiece detection circuit 34 that detects the position of the workpiece by the workpiece sensor 48 and determines whether the print start timing is correct.

Note that the components in the print head component B including the nozzle B_40 are the same as the components for performing printing with the ink ejected from the nozzle A_35 except for the plus deflection electrode and the minus deflection electrode. When a control circuit for performing printing with ink ejected from the nozzle A_35 is defined as a charging system circuit A_51, a control circuit for performing printing with ink ejected from the nozzle B_40 is defined as a charging system circuit B_52. The constituent elements of the charging system circuit B_52 are configured by elements and parts equivalent to the charging system circuit A_51.

In this embodiment, a configuration in which a plurality of nozzles are arranged in the print head 47 is employed, but the arrangement direction of the plurality of nozzles is substantially orthogonal to the deflection direction by the deflection electrodes. In addition, the charged ink particles produced from each nozzle are deflected by a pair of deflection electrodes regardless of the number of nozzles and charging electrode pairs. Furthermore, the direction of the electric field at the charging electrode and the direction of the electric field at the deflection electrode are almost orthogonal to each other.

<Disposition relationship between the print head and the workpiece and the arrangement of components inside the print head>
FIG. 5 is a diagram showing an arrangement relationship between the print head 47 and the work and an arrangement configuration of each component inside the print head 47. When printing on a workpiece using an ink jet recording apparatus, a print head cover 53 is attached and used. The interior of the print head when the print head cover 53 is removed is composed of the components shown in FIG.

As shown in FIG. 5, the print head 47 is preferably disposed obliquely with respect to the conveyance direction of the work (printed object) 49. Thereby, it is possible to prevent the printed characters from being inclined (see, for example, FIG. 2).

<Outline of printing operation with 2-nozzle configuration>
(1) Next, the printing operation according to the present invention will be described in detail. For better understanding, FIGS. 1 to 3 show the operation principle when printing is performed using a known technique for one nozzle. It explains using.

FIG. 1 is a diagram showing an example of a printing result and a charging voltage waveform when printing is performed when a work is conveyed at a certain speed in one nozzle as described above. The upper part of FIG. 1 shows the case where the particle usage rate is 1/2. A particle usage rate of 1/2 means that the voltage waveform makes one ink particle to be charged with respect to two ink particles ejected from the nozzle. In addition, the particle usage rate 1/1 means that all ink particles ejected from the nozzles are to be charged, and the particle usage rate 1/3 means that the 3 ink particles ejected from the nozzles are to be charged. This means that the number of ink particles is one. In the ink jet recording apparatus of this method, on the principle of performing printing by flying charged ink particles, the larger the particle usage rate, the less the Coulomb repulsion between charged ink particles, and the more precisely the ink landing on the workpiece. However, in this drawing, it is explained that the drawing is not considered so much.

1 is a diagram showing an example of a printing result when the charging voltage waveform is changed in the case where the work conveyance speed is the same as that in the upper stage of FIG. The middle row in FIG. 1 shows the printing result with a particle usage rate of 1/1. In comparison with the upper row in FIG. 1, the horizontal direction, that is, the column spacing in the workpiece conveyance direction is halved and the printing inclination angle is also in the vertical direction in principle. . The lower part of FIG. 1 shows the printing result when the particle usage rate is 1/1, but uncharged particles that are not charged are inserted between the columns. The column spacing can be controlled by changing the number of uncharged particles.

FIG. 2 is a diagram for explaining the principle in the case of printing an actual print character (here, “A” is taken as an example). The upper part of FIG. 2 shows the printing result at the same speed and the same charging voltage waveform as the upper part of FIG. At this time, the positional relationship between the print head 47 and the work 49 is not twisted. In this positional relationship, the charging voltage waveform and the printing result on the work when the control is performed to print “A” at a particle usage rate of 1/1 are shown in the middle of FIG.

When the positional relationship between the print head and the workpiece is not twisted, if the print result on the workpiece is tilted as shown in the middle of FIG. 2, twisting the print head is good without tilting as shown in the lower portion of FIG. Print quality can be obtained.

FIG. 3 is a diagram showing an example of a printing result when the work conveyance speed is increased in the same charging voltage waveform as that in FIG. Although the timing period when the charged ink particles land on the work is the same, the transport speed is increased, so the print interval is increased as shown in the lower part of FIG. Although the quality is deteriorated because it is extended, there is a problem that printing cannot be performed in a narrow work area due to widening of the print character width.

Based on the above operation principle, the means for increasing the particle usage rate is the most effective method for reducing the print character width even when the work conveyance speed is increased. When printing is performed, the particle usage rate of 1/1 is the maximum printing speed. Therefore, it is necessary to perform one-stage printing using two or more nozzles in order to cope with further increase in the conveyance speed. is there.

(2) Based on the above, the operation in the case of printing a character string of one stage using two or more nozzles (the present invention) will be described with reference to FIGS.

FIG. 6 is a diagram showing an example of a printing result when printing is performed with two nozzles and an example of a waveform of a charging voltage applied to ink particles ejected from the two nozzles. Printing is performed so that the printing row of nozzle B is inserted between the printing row intervals of nozzle A (printing from nozzle A and printing from nozzle B are performed alternately). As a result, it is possible to narrow the interval between the print columns, that is, to narrow the print character width, and it is possible to cope with high-speed printing.

Here, the printing row interval by printing of the nozzle A and the printing row interval by printing of the nozzle B can be printed at a certain uniform interval on the principle of operation of the ink jet recording apparatus. However, due to problems such as variations in the structural arrangement of the nozzles A and B, variations in the flying speed of each ink particle, that is, variations in timing from when the charging voltage is applied to the ink landing on the workpiece, the nozzle A Even if the interval between the print row and the print row of the nozzle B is not controlled, uniform row print cannot be realized. Therefore, with regard to this problem, it has a function that can independently adjust the timing of applying the charging voltage applied to the ink particles ejected from each nozzle, so that it is possible to evenly control the print row interval and print quality. Can be improved in quality. More specifically, first, test printing is performed, and based on the printing result, the operator uses a GUI described later (see the example of the input panel 4 (FIG. 10)) and the charging voltage generation circuit A_9 in FIG. The timing of generating the charging voltage by the charging voltage generation circuit B_23 may be adjusted.

FIG. 7 is a diagram showing an example of the result of printing on the workpiece and the example of charging voltage waveforms of nozzle A and nozzle B when the printing content “A” is actually printed. In this case, as in the case shown in FIG. 2, by rotating the print head, the inclination of characters in the print result on the work is improved, and high-quality printing as shown in FIG. 7 can be performed. It becomes.

Referring to FIG. 8, a solution to the second problem in the printing example using two nozzles (deterioration of printing quality due to inconsistent horizontal dot pitches printed from a plurality of nozzles) will be described.

The upper part of FIG. 8 shows an example of defective printing on a workpiece when the same charging voltage value is applied to each nozzle. In the ink jet recording apparatus according to the present embodiment, when the ink particles are cut in the charging electrode, a charging voltage is applied to the charging electrode to give charges to the ink particles, and the workpiece is deflected in the deflection electrode according to the amount of the charges. The principle of forming printed characters by traveling in a direction substantially perpendicular to the particle flight direction and the charged ink particle deflection direction is used. However, in this case, the amount of deflection of the charged ink particles varies due to the variation in the charge amount of the charged ink particles of the ink ejected from each nozzle and the ink flight speed. The variation is mainly caused by variations in the positional relationship between the flying ink particles and the charging electrode, the ink ejection pressure, the ink viscosity, and the like. That is, even if the repetition accuracy of a single nozzle is good, the variation between the nozzles is large, and even if the same charging voltage waveform is actually applied to the charging electrode A and the charging electrode B, the deflection amount of the charged ink particles is different. Defective printing as shown in the upper part of FIG. 8 may occur.

Regarding the problem, the inkjet recording apparatus has a function of independently adjusting the charging voltage value using the input panel 4 (GUI example (see FIG. 10)). For example, as shown in the lower part of FIG. 8, the charging voltage value changes when the character height setting value input from the input panel is varied. That is, in the case of the upper part of FIG. 8, since the voltage value applied to the charging electrode B of the nozzle B is too large (the charge amount of the ink particles is too large), the deflection amount of the ink particles from the nozzle B is the nozzle A. The amount of deflection of the ink particles is significantly different from the amount of deflection of the ink particles, but the amount of deflection of the ink particles is adjusted by adjusting the voltage value applied to the charging electrode B of the nozzle B to a small value as shown in the lower part of FIG. And is controlled to a good character height. As a result, the print quality can be improved by making adjustments while comparing with the print result on the actual workpiece.

FIG. 9 is a diagram illustrating a printing example (special pattern) that can be performed by the printing method according to the present embodiment. The upper part of FIG. 9 shows a method for realizing printing of bold characters, and the lower part of FIG. 9 shows a method for realizing printing of characters for special purposes.

As shown in the upper part of FIG. 9, when printing bold characters, the start timing of the charging voltage applied to each charging electrode is consciously adjusted, and the print width and print row interval on the workpiece are almost the same as one nozzle. 1 row is printed by two nozzles. As a result, it is possible to express one line of printing thickly, and it is possible to realize dark printing as a printing result.

In addition, as shown in the lower part of FIG. 9, when printing special-purpose characters, in addition to changing the charging voltage start timing and the charging voltage value applied to each charging electrode, the particle usage rate is changed. For example, the usage rate of particles from nozzle A is set to 1/1, and the usage rate of particles from nozzle B is set to 1/2. As a result, it is possible to realize a print example in which the inclination of the print row printed by each nozzle is variable. Thus, the method can be used for special printing applications such as symbols and logos.

<Configuration and operation of input panel (GUI)>
Next, processing from input information on the setting screen (input panel 4) to output of the charging voltage will be described with reference to FIGS. FIG. 10 shows an example of the setting screen, FIG. 11 shows a timing chart showing the charging voltage output timing for the ink particles ejected from the nozzle A and the nozzle B from the detection to the work sensor, and FIG. 12 shows the printing result at the time of this setting And an example of a charging voltage waveform.

In the setting screen example 54 according to the present embodiment, the charging voltage output timing applied to each nozzle from the work sensor detection is arbitrarily changed according to each nozzle in accordance with the print start position setting information of each nozzle input by the operator. It has a possible configuration. As shown in FIGS. 4 and 5, the circuit configuration and outline of the appearance of the ink jet recording apparatus are provided with a plurality of nozzles arranged in the traveling direction of the work that is the printing object. In this case, considering the response when the moving speed of the workpiece changes and the speed of the ink particles ejected from each nozzle are not exactly the same speed, fine adjustment of the print row interval of the ink particles ejected from a plurality of nozzles You must be able to do it. Therefore, with respect to this problem, a setting screen 54 is prepared, and the charging voltage output timing is set by allowing specific numerical values to be input for the print start position, the character height, the particle usage rate, and the print row interval adjustment. Each can be fine tuned.

First, the print start position will be described. Since the print dot and print row (scan) clocks as fine adjustment units are generated by the frequency dividing counter 16, the charging voltage output timing is delayed based on the timing signal in order to realize fine adjustment. As shown in FIG. 11, the timing for outputting the charging voltage is determined based on the print start position of each nozzle input from the setting screen 54. For example, when the print start positions from the nozzles are slightly shifted and overlapped, bold characters can be printed as described in the upper part of FIG. In the case of normal printing (when printing one stage of character string with two nozzles), the timing is set so that the print row from nozzle B is arranged in the middle between the print rows from nozzle A. (See FIG. 6).

Next, character height setting will be described. In order to cope with the problem that the ink particle speed ejected from each nozzle is not exactly the same, and the problem of non-uniformity in the character height that occurs, in this embodiment, each nozzle shares a deflection electrode. Can be adjusted. As shown in the upper part of FIG. 10, each nozzle has a character height setting function, and the setting voltage can be input independently to adjust the charging voltage width. The charging voltage width here means the difference between the charging voltage printed at the lowest level and the charging voltage printed at the highest level. The height of the printed character changes according to the charging voltage width.

As for the particle usage rate, as shown in the upper part of FIG. 10, the inclination of the print row (dot row) from each nozzle is adjusted by enabling the setting of the particle usage rate to be adjusted for each nozzle. (See the lower part of FIG. 9). Further, with respect to the print row interval adjustment value, as shown in FIG. 12, non-print dots that do not print in the print row interval are inserted for each nozzle in accordance with the print row interval adjustment value for each nozzle. By using a simple charging voltage waveform, it is possible to adjust the print row interval without changing the inclination of the print row (dot row) printed from each nozzle.

<Print dot data control>
FIG. 13 is a diagram for explaining the concept of print dot data control. Specifically, the printing dot control is based on the setting information of the input panel 4 shown in FIG. 4 as hardware components, and the MPU 1 expands the dot data in the RAM 3, and the charging voltage generation circuit A_9 and the charging voltage generation circuit B_23. Is executed by instructing the charging voltage value to be applied and the timing.

FIG. 13 shows an example of print dot data on the input panel and data assigned to the nozzles A and B with respect to the input print dot data. In other words, the dot data is printed by the MPU 1 using two nozzles such as the print dot data (b) of the nozzle A and the print dot data (c) of the nozzle B using the temporary storage area of the RAM 3. As an example, the dot data of the odd-numbered rows are alternately developed for the nozzle A, and the dot data of the even-numbered rows are alternately developed for the nozzle B for each row. Here, the odd and even columns may be reversed, but they are alternately developed for each column. For example, when there are three nozzles, the first, fourth and seventh rows are developed on nozzle A, the second, fifth and eighth rows on nozzle B, and the third, sixth and ninth rows on nozzle C. The control in the present invention can be realized.

<Summary>
In the print head of the ink jet recording apparatus according to the present embodiment, a plurality of nozzles, and charging electrodes and deflection electrodes are arranged corresponding to the plurality of nozzles. Here, the arrangement direction of the plurality of nozzles is orthogonal to the deflection direction of the charged ink particles. The control unit (MPU) of the ink jet recording apparatus expands the print characters input from the input unit into a dot matrix, assigns each dot data to a plurality of nozzles, performs an ink ejection operation from a plurality of nozzles, a plurality of The value of the charging voltage applied to the charging electrode and the application timing are controlled, and a single character string is printed on the printing object by a plurality of nozzles. By sequentially printing dot rows from a plurality of nozzles (in the case of 2 nozzles, printing is performed alternately), a single-stage character string is printed on the printing object. By doing so, it is possible to perform printing with good printing quality without widening the character width of the printing result even when the conveyance speed of the substrate is high.

The deflection electrode is composed of a pair of flat plate electrodes regardless of the number of nozzles and charging electrodes. In addition, since the deflection electrode and the DC voltage for forming the deflection electric field can be implemented in one system, an inexpensive apparatus can be provided. That is, only one power source for applying a voltage to the deflection electrode is required, and the cost of the apparatus can be reduced. Further, when there are a plurality of pairs of deflecting electrodes, there is a possibility that discharge occurs in the slit (gap) between the electrode pairs. According to this embodiment, such a situation can be prevented and ink particles can be deflected stably. Will be able to.

Further, in the present embodiment, there is a printing condition setting unit capable of setting printing conditions independently for each of the plurality of nozzles. In this case, the control unit controls the ink ejection operation, the charging voltage value, and the application timing in accordance with the printing conditions set by the printing condition input unit. Since printing can be executed while changing the printing conditions in units of nozzles in this way, fine adjustment of the printing operation can be performed in units of nozzles.

More specifically, when adjustment of the print character height is instructed by the print condition setting unit, the control unit adjusts the value of the charging voltage applied to the charging electrode corresponding to the nozzle whose print character height should be adjusted. To do. As a result, when the same voltage value is set for each nozzle, even if the printing height varies among nozzles, the height of the one-stage character string realized by a plurality of nozzles is made constant by fine adjustment. Will be able to.

Further, when the print condition setting unit is instructed to adjust the print start timing, the control unit adjusts the application timing of the charging voltage applied to the charging electrode corresponding to the nozzle whose print start timing is to be adjusted. In this way, by adjusting the print start timing between the nozzles, it is possible to adjust a subtle print timing shift between the nozzles. Further, if the print start timing is adjusted so that the print dots between the nozzles overlap, it is possible to cope with printing of special characters such as bold characters (printing of decorative characters).

In addition, when the print condition setting unit is instructed to adjust the print row interval, the control unit creates ink particles that do not print in the print row interval according to the adjustment value of the print row interval for each nozzle. By applying a charging voltage that is inserted in units of dots to the charging electrode, the print row interval is adjusted. By doing so, it is possible to realize printing of a one-stage character string with a plurality of nozzles while adjusting the print string interval in accordance with the input character string mark.

In addition, when the printing condition setting unit is set so that the particle usage rate of the ink particles ejected from each nozzle is different, the control unit controls the inclination of the dot row generated by each nozzle based on the usage rate. By doing so, a special print pattern is realized. By doing so, it is possible to cope with printing of a character string having a special shape.

As described above, various one-stage character strings can be printed by adjusting the combination of the character height, the print start timing, the print string interval, and the particle usage rate.

DESCRIPTION OF SYMBOLS 1 ... MPU, 2 ... ROM, 3 ... RAM, 4 ... Input panel, 5 ... Circulation control circuit, 6 ... Circulation system component, 7 ... Bus line, 8 ... Print start signal command circuit A, 9 ... Charging voltage generation circuit A DESCRIPTION OF SYMBOLS 10 ... Particle usage rate switch A, 11 ... Excitation setting switch A, 12 ... Transmitter A, 13 ... Phase detection circuit A, 14 ... Charge D / A converter, 15 ... AMP, 16 ... Frequency division counter A, 17 ... Excitation voltage generation circuit A, 18 ... AMP, 19 ... AMP, 20 ... deflection D / A converter, 21 ... AMP, 22 ... print start signal command circuit B, 23 ... charge voltage generation circuit B, 24 ... particle usage rate switch B , 25 ... Excitation setting switch B, 26 ... Transmitter B, 27 ... Phase detection circuit B, 28 ... Charging D / A converter B, 29 ... AMP, 30 ... Frequency division counter B, 31 ... Excitation voltage generation circuit B, 32 ... AMP, 33 ... AM 34 ... Printed object detection circuit, 35 ... Nozzle A, 36 ... Electrostrictive element A, 37 ... Charging electrode A, 38 ... Phase search sensor A, 39 ... Gutter A, 40 ... Nozzle B, 41 ... Electrostrictive element B 42 ... Charging electrode B, 43 ... Phase search sensor B, 44 ... Gutter B, 45 ... Deflection electrode-, 46 ... Deflection electrode +, 47 ... Print head, 48 ... Work sensor, 49 ... Work, 50 ... Conveyor, 51 ... Charging system circuit A, 52 ... Charging system circuit B, 53 ... Print head cover, 54 ... Setting screen (GUI) example

Claims

An inkjet recording apparatus for printing on a substrate to be conveyed,
Multiple nozzles,
A plurality of charging electrodes arranged to correspond to the plurality of nozzles and for charging ink particles ejected from each of the plurality of nozzles;
A deflection electrode for deflecting the charged ink particles;
An input section for inputting print characters;
The print characters input from the input unit are expanded in a dot matrix, each dot data is assigned to the plurality of nozzles, ink ejection operation from the plurality of nozzles, and the charging voltage applied to the plurality of charging electrodes. A control unit for controlling the value and the application timing,
An ink jet recording apparatus, wherein an arrangement direction of the plurality of nozzles is orthogonal to a deflection direction of the charged ink particles, and a character string of one stage is printed on the printing object by the plurality of nozzles.
In claim 1,
2. The ink jet recording apparatus according to claim 1, wherein the deflecting electrode includes a pair of flat plate electrodes regardless of the number of the nozzles and the charging electrodes.
In claim 1,
The input unit has a printing condition setting unit capable of setting printing conditions independently for each of the plurality of nozzles,
The ink jet recording apparatus, wherein the control unit controls the ink ejection operation, the value of the charging voltage, and the application timing in accordance with the printing condition set by the printing condition input unit.
In claim 3,
When the printing condition height is instructed by the printing condition setting unit, the control unit adjusts the value of the charging voltage applied to the charging electrode corresponding to the nozzle whose printing character height should be adjusted. An ink jet recording apparatus.
In claim 3,
When the adjustment of the print start timing is instructed by the print condition setting unit, the control unit adjusts the application timing of the charging voltage applied to the charging electrode corresponding to the nozzle to adjust the print start timing. An ink jet recording apparatus.
In claim 3,
When the adjustment of the print row interval is instructed by the print condition setting unit, the control unit sets the non-printed dots that are not printed in the print row interval to the ink particles according to the adjustment value of the print row interval for each nozzle. An inkjet recording apparatus, wherein the print row interval is adjusted by applying a charging voltage to be inserted in units of created dots to the charging electrode.
In claim 3,
When the printing condition setting unit is set so that the particle usage rate of the ink particles ejected from each nozzle is different, the control unit calculates the inclination of the dot row generated by each nozzle based on the usage rate. An ink jet recording apparatus that realizes a special print pattern by controlling.
In claim 3,
The said control part prints the said 1 step | paragraph character string on the said to-be-printed material by performing the printing of the dot row from these nozzles in order, The inkjet recording device characterized by the above-mentioned.
A print head used in an ink jet recording apparatus,
Multiple nozzles,
A plurality of charging electrodes arranged to correspond to the plurality of nozzles and for charging ink particles ejected from each of the plurality of nozzles;
A deflection electrode for deflecting the charged ink particles;
A print head, wherein an arrangement direction of the plurality of nozzles is orthogonal to a deflection direction of the charged ink particles.
In claim 9,
A print head, wherein an electric field direction at the charging electrode is orthogonal to an electric field direction at the deflection electrode.
In claim 9,
The print head according to claim 1, wherein the deflection electrode is composed of a pair of flat plate electrodes regardless of the number of the nozzles and the charging electrodes.